It is known that 1,3,5-trimethyl-2,4,6-tris(3,5-dialkyl-4-hydroxybenzyl)benzenes can be prepared by reacting mesitylene with the appropriate 2,6-dialkyl-4-methoxymethylphenol in the presence of an acidic catalyst, usually sulfuric acid. It is also known that the use of sulfuric acid in an amount sufficient to provide the desired product in good yields has presented a severe spent sulfuric acid disposal problem in commercial operations.
As taught in U.S. Pat. Nos. 4,992,597 (Mina et al.) and 4,994,628 (Goddard et al.), this disposal problem can be minimized by conducting the mesitylene/2,6-dialkyl-4-methoxymethylphenol reaction under temperature and pressure conditions such that methanol by-product formed by the reaction distills out of the reaction mixture as it is formed. The co-distillation technique permits the desired product to be provided in high yield with the use of considerably smaller amounts of sulfuric or sulfonic acid catalyst than were previously thought necessary to provide a 1,3,5-trimethyl-2,4,6-tris(3,5-dialkyl-4-hydroxybenzyl)benzene containing commercially-unacceptable amounts of by-products.
Although Mina et al. and Goddard et al. teach that their reactions may be conducted in hydrocarbon solvents instead of their preferred halohydrocarbon solvents, it has not been found possible to obtain good product yields when a hydrocarbon solvent is employed. This is particularly unfortunate because of the present desirability of avoiding the use of halohydrocarbon solvents--especially those which are already highly regulated and believed to be potentially damaging to the ozone layer.